Safety catch for vertically sliding doors



Jan. 20, 1959 2,869J83 SAFETY CAICH FOR VERTICALLY SLIDING DOORS W. 0. SMITH 2 Sheets-Sheet 1 Filed April 14, 1958 ATTORNEY 2,8695183 SAFETY CATCH FOR VERTICALLY' SLIDING nooas Filed April 14, 1958 W. 0. SMITH Jan. 20, 1959 2 Sheets-Sheet 2 4- INVENTOR ATTORNEY United rates SAFETY CATCH FQR VERTICALLY SLIDING DOORS A This invention relates to a novel safety catch for vertical sliding doors, which are usually of the overhead type and which are raised and lowered by cables or similar flexible members, which support the entire weight of the door while it is being raised or lowered.

A primary object of the present invention is to provide a safety device which is automatically rendered operative by breakage of such a supporting cable or where the tension on the cable is released, as for example, due to failure of mechanically operated cable drums, for immediately latching the door to prevent falling of the door.

More particularly, it is an aim of the present invention to provide a safety latch of extremely simple construction which is held in a released position by the tension of a door supporting cable and immediately assumes a latching position for supporting the door when the tension of the supporting cable is released from the latch.

Still another object of the invention is to provide a safety latch which is spring urged toward an operative latching position against the tension of a supporting cable of the door, including means for varying the spring tension tending to urge the latch to an engaged position, depending upon the position of the door relative to a fully opened and fully closed position thereof.

Various other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, illustrating a presently preferred embodiment thereof, and wherein:

Figure l is a fragmentary front elevational view of a lower corner of a vertical sliding door or closure and showing the safety latch applied thereto; 7

Figure 2 is a fragmentary edge elevational view, partly broken away and partly in vertical section, looking from right to left of Figure l;

Figure 3 is a fragmentary horizontal sectional view taken substantially along a plane 'as indicated by the line 3-3 of Figure 1;

Figure .4 is a fragmentary vertical sectional view taken substantially along a plane as indicated by the line 44 of Figure 3;

Figure 5 is an enlarged fragmentary vertical sectional view in detail, taken substantially along a plane as indicated by the line 5-5 of Figure l, and

Figure 6 is a substantially horizontal sectional view, taken substantially along the line f66 of Figure 5.

Referring more specifically to the drawings, for the purpose of illustrating the application and operation of the safety latch, designated generally 8 and comprising the invention, a portion, constituting a lower corner, of a vertically sliding door 9 is illustrated in the drawings together with a portion of a conventional track or guideway 10 which is spaced outwardly from the vertical side edge 11 of the door 9.

The safety latch 8 includes amounting plate 12 which is secured against the inner side of the bottom corner of the door 9 by suitable fastenings 13, and which has an inturned bottom flange 14, as seen in Figure 2, which bears against the bottom edge of said center of the door meat 0 "ice 9, so that the weight of the door which is borne by the latch structure 8 will be supported by the bottom flange 14 rather than by the fastenings 13.

The safety latch 8 includes a rack bar 15 which is secured to the outer wall 16 of the track 10 and extends vertically therewith from top to bottom of the track 10. The rack bar 15 has an outer edge provided with teeth 17 which are spaced outwardly from an outer or front wall 18 of the track 10. The teeth 17 are provided with upwardly facing shoulders 19, as seen in Figures 2 and 4, which have a positive rake, that is, are inclined downwardly and inwardly relative to the rack bar 15. A cam rail 20 is secured to and projects outwardly or forwardly from the inner front wall 21 of the track 16. As best seen in Figures 2 and 4, the outer forward edge 22 of the cam rail 20 is disposed at a slight incline upwardly and inwardly, relative to the front wall 18 of the track 10. Thus, the front edge 22 is disposed outwardly or forwardly of the plane of the front wall 18 a maximum distance at the lower end of said cam rail Zll, which is disposed at the lower end of the track 10, and said outer edge 22 gradually converges with the plane of said wall 18 toward the upper end of the track lit and ceases to be disposed outwardly with respect thereto adjacent the topmost portion ofthe track 10. For the purpose of clarity, the incline of said rail edge 22 is exaggerated in Figures 2 and 4.

A pair of aligned bearings 23 are fixed to and project outwardly from the lower portion of the mounting plate 12 for journaling a shaft 24 with its axis disposed substantially horizontal. The shaft 24 projects outwardly beyond the door edge 11 and into the track 1% through the open inner side 25 thereof. A wheel 26 is secured to the outer end of the shaft 24 and is disposed in the track 10 in engagement with the inner side of its front Wall 18. The wheel 26 and shaft 24 are conventional and are merely mounted in bearings 23 fixed to the plate 12 rather than in bearings which are secured directly to the door, as is conventional.

A pair of horizontally spaced aligned bearings 27 and 28 are fixed to and project outwardly from the upper portion of the mounting plate 12 to provide journals for a shaft 29 which extends therethrough. An arm St) is fixed to an end of the shaft 29, which is disposed adjacent the door edge 11, and said arm extends outwardly and upwardly from the shaft 29 and is provided with a sleeve portion 31 at its upper end which is disposed parallel to the shaft 29. A restricted threaded stem 32 of a shoulder bolt extends inwardly through the sleeve 31 and is secured therein by a nut 33. A roller 34 is journaled on the enlarged end 35 of the shoulder bolt and is supported to engage the cam rail edge 22 or the outer wall 13 of the track It as seen in Figures 1 and 3. A torsion spring 36 is loosely disposed around a part of the shaft 29 between the bearings 27 and 28 and has one end 37 anchored in the bearing 27 and its opposite end 38 anchored in a winding collar 39. The collar 39 is rotated about the shaft '29 to tension the spring 35 to a desired extent, and the setscrew 40 of said collar is then tightened against the shaft, 29 for securing the collar immovably to said shaft. The spring 36 urges the shaft 29 and the arm 30 to turn in a direction to yieldably retain the roller 34 against the cam rail edge 22. or in engagement with the track wall 18.

A second pair of horizontally spaced aligned bearings 41 and 42 are fixed to and project outwardly from the plate 12, beneath the bearings 27 and 28 for journaling a shaft 43. An arm 44 is fixed to an end of the shaft 43 which extends outwardly beyond the plane of the door edge 11. The arm 44 extends outwardly from the shaft 4-3 and has a lateral branch 45 at its outer end which extends outwardly across the track 10, as best seen in Figures 1 and 3. A pawl shank 46 is fixed to and extends upwardly from the terminal portion of the arm branch 45 and is disposed in the plane of the rack bar 15. The pawl shank 4-6 terminates at its upper end in a pawl head 47 which is substantially wider than the thickness of the rack and which has an inwardly extending tapered nose 48 for engaging between the teeth 17. The underside of the nose 48 is inclined so as to bear flush on the shoulder 19 of any one of the teeth 17 when the pawl 47 is swung inwardly to a latching position. An arm 49 is rigidly secured to the aforementioned end of, the shaft 43 and extends inwardly therefrom, or in the opposite direction to the arm 44, as seen in Figures 2, 3 and 4. The terminal portion of the arm 49 extends across the door edge 11 and has an end of a cable 50 anchored thereto. The cable portion 50 constitutes a lower end of one of a pair of conventional cables utilized to raise and lower the door 9 and the lower ends of which are normally attached directly to lower portions of the door at or adjacent the side edges thereof, and which cables have upper portions connected to cable drums, not shown, or other mechanism which is power-operated for drawing in or paying out the cables simultaneously for raising or lowering the door 9, respectively. The safety latch 8, constituting the invention, is adapted for use with any flexible element and any type of cable drum or hoist means thereof.

A rigid bar 51 is fixed to the plate 12 and extends outwardly therefrom beneath the arm 44. A screw 52 is threaded upwardly through the bar 51 and bears against the underside of the arm 44, near the free end of said arm. A jamb nut 53 threadedly engages the screw 52 and bears against the underside. of the bar 51 to retain the screw 52 in different adjusted positions. The bar 51 and screw 52 provide a stop to limit downward swinging movement of the arm 44 and thus sustain a part of the weight of the door which is borne by the cable 50. Said adjustable stop 51, 52 also limits the extent that the pawl nose 48 can be swung outwardly to a released position away from the rack bar teeth 17.

A collar 53 is fixed to the end of the shaft 29, which is disposed remote from the arm 30, and has an arm 54 ex tending outwardly therefrom. The arm 54 has a downwardly extending outer portion 55 which is provided with a slot 56 extending substantially the length thereof and which opens outwardly of the lower end of the portion 55. A collar 57 is fixed to the shaft 43 and is disposed beneath the collar 53, as seen in Figure 1. As seen in Figure 2, an arm 58 is fixed to and extends upwardly from the collar 57. A stem 59 is fixed to and extends outwardly from the arm 58 and projects loosely through the slot 56, as best seen in Figures 2 and 5. A yieldable cup member 60 is mounted on the stem 59 and against the arm 58 and has an outwardly opening socket 61 which is tapered inwardly and then flared at its bed to seat an end convolution of a compression spring 62 which fits loosely on the stem 59 between the cup member 60 and the arm portion 55. The opposite end of the spring surrounds the restricted inner end 63 of a spring abutment 64 and bears against an annular inwardly facing shoulder 65, which surrounds said restricted end 63. The spring abutment 64 has an outwardly tapered nose 66 the restricted outer end of which extends into the slot 56 and has a point to point contact with corresponding edges of the ann portion 55 which forms said slot 56, as seen in Figure 6, so that said spring abutment 64 and the arm portion 55 may readily slide relative to one another with a minimum of frictional resistance. The spring abutment 64 is slidably mounted on the stem 59.

As seen in Figures 1, 2 and 3, a bar 67 is fixed to and extends outwardly from the base plate 12 and has a setscrew 68, which carries a jamb nut 69, threaded downwardly through a part thereof which is disposed over the arm portion 54, so that the parts 67 and 68 form an adjustable stop for limiting upward swinging movement, of

4 the arm or bracket 54, 55 and thus limit turning movement of the shaft 29.

The door '9 is of the conventional type wh1ch assumes a substantially horizontal overhead open posltlon and when thus disposed the roller 34 is out of engagement with the cam rail 20. When thus disposed, a minimum pull is exerted on the arm 49 by the cable 50 and the tension of the spring 70 is adjusted so that it will be insufficient to swing the pawl 47 inwardly while such minimum cable pull is being exerted by the cable St). The spring 70 constitutes a torsion spring corresponding with the torsion spring 36 and is loosely mounted on the shaft 43 between the bearing 41 and a winding collar 71 which corresponds to the collar 39.

' One end of the spring 70 is anchored to the bearing 41 and the other end thereof is anchored to the collar 71 so that adjustment of the spring 71 is accomplished by rotating and securing the collar to the shaft 43, in the same manner as previously described in reference to adjustment of the tension of the spring 36. Thus, the spring 70 provides the only force tending to urge the pawl 47 to a latching position and which lacks sufficient power to accomplish this even when a minimum pull is being exerted by the cable 50, unless breakage of the cable or failure of the cable winding mechanism occurs.

As the door 9 is lowered the roller 34 moves into contact with the rail edge 22 and is gradually forced outwardly thereby to turn the shaft 29 against the tension of its torsion spring 36 and whereby the bracket or arm 54, 55 is swung downwardly and inwardly, as seen in Figure 2. When this occurs, the arm portion 55 forces the spring abutment 64 inwardly of the stem 59 for compressing the spring 62, which was previously fully released. As the spring 62 is compressed it yieldably urges the arm 58 and shaft 43 to turn clockwise as seen in Figure 2 and thus yieldably urges the latching pawl 47 inwardly and toward the rack bar 15. Thus, as the door 9 moves downwardly or toward a position where a greater load is supported by the cable 50, the latching pawl 47 is progressively subjected to increased pressure urging it toward a latching position. Conversely, and as the door 9 is raised from a fully lowered position, the latching pawl 47 initially has a maximum pressure thereon urging it toward a latching position and as the door rises and the load on the cable 50 diminishes, the spring tension on the pawl 47 likewise diminishes due to travel of the roller 34 up the diminishing cam surface 22 so that the spring 36 can act to gradually turn the shaft 29 clockwise, as seen in Figure 2, to swing the bracket portion 55 outwardly for diminishing the compression of the spring 62.

It will be understood that if the cable 50 breaks or goes slack that the action of the spring 70', alone or in combination with the compressed spring 62, will move the pawl nose into engagement between two of the teeth 17 and the flush engagement of the underside of the pawl nose 48 with the downwardly and inwardly inclined shoulder 19 of one of the teeth 17 will effectively urge said pawl nose inwardly of the rack bar to a fully latched position.

It will be understood that only one of a pair of the safety latches 8 has been illustrated and described and that a second safety latch 8 will be mounted on the other lower corner of the door 9 to function with the other supporting cable 50, not shown, and with the other track 10, not shown.

Various modifications and changes are contemplated and may be resorted to, without departing from the function or scope of the invention as hereinafter defined by the appended claims.

I claim as my invention:

1. In combination with a vertically sliding door or closure, a flexible element for raising, lowering and supporting the door, an upright guide track disposed adjacent a side edge of the door and a guidewheel carried by the E W4vr v v door and movably engaging in said track; a safety latch to' prevent dropping of the door due to breakage or release of said flexible element, comprising a toothed latch bar fixed to said guide track and having a toothed edge projecting outwardly from a front side of the tracii, a latching pawl for releasably engaging between teeth of said latch bar, a shaft to which the latching pawl is secured, bearings associated with the door in which the shaft is journaled, a lever arm fixed to the shaft and to which said flexible element is connected for connecting the flexible element to the door, the pull of the flexible element against the lever acting to turn the shaft to rock said pawl in a direction for urging and holding the pawl in a released position out of engagement with the latch bar teeth, a first spring associated with said shaft and urging the pawl toward the latch bar and into a latching position, a second spring acting, when compressed, with said first spring for urging the pawl toward a latching position, means carried by the door and engaging a stationary part carried by the guide track for exerting a variable pressure against said second spring for varying the pressure of the second spring depending upon the position of the door relative to a fully opened and a fully closed position, the combined power of said springs being less than the power exerted on the lever by said flexible element when the flexible element is taut.

2. In a combination as defined by claim 1, lever members between which said second spring is disposed, one of said lever members being fixed to said shaft, said other lever member constituting a part of said last mentioned means, said means including a second lever element pivotally supported by said door and provided with a roller journaled on a free end thereof, and said part of the means carried by the guide track including an inclined cam rail engaged by said roller.

3. In combination with a vertically sliding door or closure, a flexible element for raising, lowering and supporting the door, an upright guide track disposed adjacent a side edge of the door and a guide Whfil carried by the door and movably engaging in said track; a

safety latch to prevent dropping of the door due to breakage or release of said flexible element, comprising a toothed latch bar fixed to said guide track and having a toothed edge projecting outwardly from a front side of the track, a latching pawl for releasably engaging between teeth of said latch bar, means pivotally supporting said pawl on the door, a lever arm projecting from said means and to which said flexible element is connected for connecting the flexible element to the door, the pull of the flexible element against the lever acting to rock said pawl and the means in a direction for urging and holding the pawl in a released portion out of engagement with the latch bar teeth, spring means associatedwith said pawl and urging the pawl toward the latch bar and into a latching position, the power of said spring means being less than the power exerted on the lever by said flexible element when the flexible element is taut, and means including a fixed part supported by the guide track and a movable part carried by the door and engaging said fixed part for increasing the force exerted by said spring means on the pawl as the door moves downwardly toward a closed position and for reducing the force exerted by the spring means on the pawl as the door moves upwardly toward an open position.

4. In a combination as defined by claim 3, a plate detachably secured to the bottom portion of the door and supporting the parts of said safety latch carried by the door.

5. In a combination as defined by claim 4, and an adjustable stop supported by said plate and disposed to be engaged by a part of the latching pawl for limiting movement of the latching pawl toward a released position.

6. A safety latch for a vertically sliding door comprising an elongated stationary toothed latch bar adapted to be secured to an upright guide track, a latching pawl, means adapted to be carried by a lower portion of a vertically sliding door for pivotaily supporting said pawl for swinging movement into and out of engagement with the teeth of the latch bar, spring means carried by said aforementioned means and urging said pawl to a latching position in engagement with the teeth of the latch bar for latching the door against downward movement, a lever arm fixed to the pawl at the pivot means and extending away from the pawl, said lever arm being adapted to be secured to an end of a flexible door suspending element for connecting said element to the door, the pull on said element resulting from the weight of the door being suflic'ient to overcome the power exerted by said spring means for retaining the pawl in a released position out of engagement with the latch bar when the flexible element is taut, said spring means including an inclined cam rail adapted to be supported by the guide track and a leverage means adapted to be carried by the door and engaging said cam rail and operable to increase the force exerted by said spring means as the door moves downwardly and for reducing the force exerted by the spring means as the door rises.

7. A safety latch as in claim 6, and an adjustable stop adapted to be fixedly supported by the door and normally engaged by a part of the pawl for sustaining the pull exerted by the flexible member.

References Cited in the file of this patent UNITED STATES PATENTS 1,404,053 Peele Jan. 17, 1922 2,238,963 Bayer Apr. 22, 1941 2,388,654 Holmes Nov. 6, 1945 2,475,015 Crocker et al. July 5, 1949 2,651,817 Moler Sept. 15, 1953 

